Many electrical circuits are intended to be used on commercial frequency power lines such as 60 Hz, 115/230 V AC. However, sometimes the commercial power line has an outage and it is then desireable to have an emergency power circuit to power such loads.
A typical emergency power supply, for example, for computers is to have a storage battery operating through an inverter to supply the same 60 Hz, 115/230 V AC output to the computer so that it is connected immediately upon failure of the commercial power line voltage. The computer may take only a few hundred watts and therefore the physical size and capacity of the emergency power supply is rather small. However, when the load is substantial, such as a home elevator, chair lift, wheel chairlift, etc., the physical size and cost of such an emergency power supply having an output at 60 Hz and 230 V AC becomes economically prohibitive.
An object of the invention, therefore, is to provide an emergency power supply of reduced physical size and electrical output capacity which still may be able to operate a substantial electrical load such as a home elevator, chairlift, wheel chairlift, etc.
Another object of the invention is to provide an emergency power circuit for an induction motor having at least first and second windings.
Another object of the invention is to provide an emergency power system to operate an electrical load at less than normal speed in order to reduce the power requirements.